Convergence of Science and Engineering to Develop Tissue-on-Chip SystemsBiological organs and tissues function in 3D. Yet our understanding of biology has largely been defined by microscopy and in vitro cell culture, both of which are inherently 2D. We need model systems that recapitulate the 3D interactions of different cell types in tiny organs that we can manipulate and analyze to study normal function, pathogenesis, regeneration and therapy. To this end, biomedical engineers are combining science and technology from cell biology, physiology, microfluidics, microfabrication, and imaging to create tiny tissues on chip. As examples, I will describe the status of our studies on microvasculature for integration into heart, skin, and lung tissue-on-chip and complex assemblies that differentiate into gut-on-chip.